What's the difference between college graduates and non-college graduates?

If you said "college" you are correct. Duh. 

But lots of folks think it's a trick question. 

[Boldface is added by me throughout.] 

What we know: the heart of the Trump coalition was non-college whites. See, here, here, here, and here (Even Among the Wealthy...).

Based on an observed correlation between not-going-to-college and voting for Trump, a scientist would form a hypothesis like: what is it about graduating from college that either causes people to like Hillary Clinton or prevents them from liking Donald Trump?

Instead what we have is analogous to the link between smoking and cancer... leading folks to assert things like "spending money in gas station mini-marts causes cancer." To wit...

Trump's victory was caused by:

Hillary Clinton, by contrast, epitomizes the dorky arrogance and smugness of the professional elite. The dorkiness: the pantsuits. The arrogance: the email server. The smugness: the basket of deplorables. Worse, her mere presence rubs it in that even women from her class can treat working-class men with disrespect. Look at how she condescends to Trump as unfit to hold the office of the presidency and dismisses his supporters as racist, sexist, homophobic, or xenophobic.

What if it is simply the case that they believe David Brooks when he says (correctly):

In these places [Red America], the crucial inequality is not between the top 1 percent and the bottom 99 percent. It’s between those with a college degree and those without. Over the past several decades, the economic benefits of education have steadily risen. In 1979, the average college graduate made 38 percent more than the average high school graduate, according to the Fed chairman, Ben Bernanke. Now the average college graduate makes more than 75 percent more.
Moreover, college graduates have become good at passing down advantages to their children. If you are born with parents who are college graduates, your odds of getting through college are excellent. If you are born to high school grads, your odds are terrible.
In fact, the income differentials understate the chasm between college and high school grads. In the 1970s, high school and college grads had very similar family structures. Today, college grads are much more likely to get married, they are much less likely to get divorced and they are much, much less likely to have a child out of wedlock.
Today, college grads are much less likely to smoke than high school grads, they are less likely to be obese, they are more likely to be active in their communities, they have much more social trust, they speak many more words to their children at home.

Academic studies of the white working class ignore the centrality of college that is right in front of their face

The quotation above about dorky Hillary comes from Joan C. Williams, a professor at University of California, Hasting College of Law, whose next book is called White Working Class. She lays out a plan for Democrats that you've heard many times from Bernie, et al, "Place Economics At The Center" and "Avoid the Temptation to Write Off Blue-Collar Resentment as Racism." But before she does, look at what she says in the set-up part of her piece, the part where she's laying out how stupid Democrats are: 

Class migrants (white-collar professionals born to blue-collar families) report that “professional people were generally suspect” and that managers are college kids “who don’t know shit about how to do anything but are full of ideas about how I have to do my job,” said Alfred Lubrano in Limbo.

Another version of the same book has been written by Kathy Cramer of the University of Wisconsin (The Politics of Resentment). Below she is talking to the WaPo about what the white working class resents. The italics are in the WaPo original and represent Cramer speaking in the voice of the non-college whites she has studied.

For example, people would say: All the decisions are made in Madison and Milwaukee and nobody’s listening to us. Nobody’s paying attention, nobody’s coming out here and asking us what we think. Decisions are made in the cities, and we have to abide by them. 
... 
When people are talking about those people in the city getting an “unfair share,” there’s certainly a racial component to that. But they’re also talking about people like me [a white, female professor]. They’re asking questions like, how often do I teach, what am I doing driving around the state Wisconsin when I’m supposed to be working full time in Madison, like, what kind of a job is that, right?
... 
Oftentimes in some of these smaller communities, people are in the occupations their parents were in, they’re farmers and loggers. They say, it used to be the case that my dad could do this job and retire at a relatively decent age, and make a decent wage. We had a pretty good quality of life, the community was thriving. Now I’m doing what he did, but my life is really much more difficult.
I’m doing what I was told I should do in order to be a good American and get ahead, but I’m not getting what I was told I would get.

Notice that the last claim is false:

I’m doing what I was told I should do in order to be a good American and get ahead, but I’m not getting what I was told I would get.

Do we really tell people that "to get ahead" you need to graduate high school and get a job? Unless rural white people don't have access to televisions, they know good and well by now that "getting ahead" requires a college education. 

Finally, look at what people have proposed as the cure to our political dysfunction and ask yourself: Where do we foster scientific curiosity? Where do we inculcate liberal values and norms? Where do we teach people how to speak about race, sexuality and gender in a way that prevents harm to vulnerable people? If people missed that opportunity to learn when they were 18, are we likely to persuade them now when they are 55?

Here's Brian Resnick at Vox.com writing about the work of Dan Kahan:

While we would like to believe we can persuade people on the other side of a political debate with evidence, his studies show the other side is likely to become even more deeply entrenched in its view in the face of more information. His findings are a blow to the great underlying assumption of democracy: that an informed public isthe keyfor a government that works.
The phenomenon is called “politically motivated reasoning,” and it finds people use their minds to protect the groups to which they belong from grappling with uncomfortable truths. The motivation to conform is stronger than the motivation to be right.
That’s why his latest research finding “is totally unexpected,” he says. There’s an antidote to politically motivated reasoning, it turns out. And it’s wonderfully simple: curiosity.

Steve Randy Waldman writing on his blog Interfluidity titles his piece "Persuade"

When Trump supporters complain about “political correctness”, they are claiming that contemporary liberal norms have rendered it socially costly for them to speak freely and candidly even when they mean no harm. They may be wrong to complain. Perhaps stigmatizing all but the most careful forms of expression around matters of race and sexuality and gender is in fact the best way to prevent severe harms to vulnerable people, and is a development that should be celebrated. Regardless, many Americans, whether they are right or wrong and even if they are mostly white, perceive a cost in personal freedom to these norms. They have not been convinced that those costs are just or necessary, especially in light of their own increasing vulnerability and grievance. Whether or not their discontent is legitimate, whether or not they are right to assert an ethical problem, their perception constitutes a political problem.
... 
Ours is a political coalition that considers itself rational and open-minded, tolerant and cosmopolitan, and in many respects I think that is right. Multiculturalism means not fearing what is ugly in other cultures (and let’s not be so chauvinistic as to imagine we have a monopoly on ugly), but instead embracing what is wonderful. It means placing faith in the capacity of all of our better angels to guide us towards mutually enriching coexistence rather than mutually destructive conflict. We take pride in embracing and respecting people who look and act very differently than we do, who follow strange creeds the substance of which we might disagree with, who follow customs that may render us uncomfortable and require an unusual degree of diplomacy when we are called to interact in any intimacy. These habits and skills, of which I think we are justly proud, are precisely what are required of us now. If we can be as open and charitable and welcoming and diplomatic across the fault lines which have snuck up within our politics as we are towards those we more easily recognize as outsiders, we have a real shot, not only to reconfigure the electoral numbers game, but also to forge a shared understanding that would transform what must begin as a pragmatic exercise in politics into an ethical enterprise after all.